The present invention is directed to an apparatus for introducing CO2 snow into containers for cooling the container contents or the container. The apparatus has a CO2 snow-generating means for generating CO2 snow, a CO2 snow injection means connected to the CO2 snow generating means a snow tube for the injection of the generated CO2 snow into the container, a CO2 gas separating means for the separation of CO2 gas and CO2 snow in the region of the snow tube and a CO2 gas extraction means for extracting separated CO2 gas. What is to be understood here by generating CO2 snow is that conditions are created whereat CO2 snow arises.
In many technical processes, the product to be processed must have its temperature maintained within a specific range in order to avoid damage to or poorer workability of the product. Due to the introduction of mechanical energy, for example in the form of mixing or homogenizing, the temperature in the container rises and, thus, so does the temperature of the product. Some materials exhibit low thermal conductivity, a great layer thickness, a high viscosity or other properties during the processing process that require a direct cooling. When producing doughs in a bakery, for example, the temperatures are to be kept as constant as possible in the range from 23xc2x0 C. through 30xc2x0 C. (for example, 24xc2x0 C.+/xe2x88x920.5xc2x0 C.) dependent on the various types of baked goods in order to be able to govern the biological, enzymatic and chemical processes so that the processes, which are critical for the dough preparation are undiminished. Even temperature fluctuations of 1 through 2xc2x0 C. already lead to significantly modified product properties. The reasons for this include the narrow temperature optimum of the enzymes contained therein as well as of the added baker""s yeast. Thus, the respiratory activity and, thus, the CO2 formation rate of the yeast is directly dependent on the process temperature. The dispersion of the solids, the gas solubility, the gas pressure, the plastic, elastic and viscous properties are also influenced by the temperature. Up to now, water in the form of faked, cracked or chipped ice was often utilized for direct cooling. This cooling method, however, has a physical limit since the proportion of water in the product is also raised due to intensified cooling. Due to the predetermined proportion of water in the product, water as ice can be added only maximally on this order of magnitude. Whereas to 100% of the added water can be added as ice in a butcher shop during the process of cutting, only 10 through 20xc2x0 of the added water can be added as ice in a bakery, since the remaining part must already be present as a liquid (rising, stabilization) at the beginning of the dough structuring (working).
A direct cooling of raw materials, intermediate and final products requires an innocuous nature of the coolant in the product to be processed not only in the food stuffs field but also in the field of pharmaceutics and cosmetics. It is also important that no dilution or some other modification of the concentrations as is possible given a direct cooling with water as ice occurs in the product due to the cooling process. A direct cooling with CO2 snow meets these criteria.
As a result of the employment of CO2 snow in the direct cooling of the product, the energy transport can be decoupled from the amount of water utilized. Since a great deal of energy is withdrawn from the product (for example dough) due to the high evaporation enthalpy of the CO2 in the phase transition from a solid to a gaseous phase (sublimation), a direct cooling with CO2 snow is thus very efficient. Due to an enrichment of CO2 in the gas phase, however, a reduction of the partial oxygen pressure in the head space of the container occurs. A specific partial oxygen pressure is necessary, for example in dough production, for the processes of oxidative solidification of the adhesive lattice due to the interaction of thiol and disulfide groups. As a result of the extraction of the gaseous CO2 from the head space, the necessary partial oxygen pressure for assuring these oxidative processes can be adhered to.
The known apparatus cited at the outset exhibits the disadvantage that devices that are already present such as, for example, dough agitators can be refitted with a dough or, respectively, container cooling only with relatively great structural outlay.
The invention is thus based on the object of developing the known apparatus to the effect that already existing devices can be easily retrofitted with a dough or, respectively, container cooling.
This object is inventively achieved in that the CO2 gas separating means comprises an outside tube that surrounds the snow tube and is coaxially arranged thereto that projects beyond the snow tube in a longitudinal direction thereof at the CO2 snow output side of the snow tube and that is connected with the CO2 gas extraction means in the region of the opposite side.
It can thereby be provided that the CO2 snow generating means comprises a delivery means for conducting liquid CO2 and an evaporation means for the evaporation of the liquid CO2.
Beneficially, the evaporation means is arranged in the region of that side of the snow tube lying opposite the CO2 snow delivery side.
The evaporation means advantageously comprises a nozzle.
Beneficially, the snow tube and the outer tube end in the head space of the container.
It can also be provided that the snow tube and the outer tube are vertically arranged.
On the other hand, it can also be provided that the snow tube and the outer tube are arranged at such an angle that the CO2 snow drops into the container.
Beneficially, the snow tube is widened at the CO2 snow delivery side. A more uniform output of the CO2 snow into the container is thus assured.
It can also be provided that the outer tube is widened at its end located at the CO2 snow delivery side of the snow tube.
In particular, it can be provided that the snow tube and/or the outer tube is/are conically fashioned.
Beneficially, the extraction means comprises a ventilator.
According to another particular embodiment, the apparatus is characterized by a temperature control means for regulating the temperature of the container content or of the container itself by the injection of a corresponding quantity of the CO2 snow.
In particular, it can thereby be provided that the temperature control means comprises a rated temperature input means, a temperature sensor for measuring the actual temperature of the container content, a temperature comparison means for comparing the actual temperature to the rated temperature as well as a drive means for driving a valve arranged in the supply conduit for the liquid CO2.
Another particular embodiment of the invention is characterized by an oxygen partial pressure regulating means for regulating the partial oxygen pressure in the head space of the container by extracting a corresponding quantity of the CO2 gas.
Alternatively, a particular embodiment can be characterized by a carbon dioxide partial pressure regulating means for regulating the partial carbon dioxide pressure in the head space of the container by measuring the partial carbon dioxide pressure and extracting a corresponding quantity of the CO2 gas. Compared to the embodiment with oxygen partial pressure regulating means, the CO2 gas part is directly measured in this embodiment.
Finally, it can be provided that the container is a container for kneading bread or cake dough.
The invention is based on the surprising perception that the concentric arrangement of the snow tube and the surrounding outer tube of the separating means results merely in a double tube and, thus, a structural intervention for passing the double tube through need only be undertaken at one location of the container cover for retrofitting existing devices with the dough or container cooling. Over and above this, the snow tube that is shorter compared to the outer tube enables an extraction of the CO2 not converted into CO2 snow before the CO2 gas enters into the container at all, which enables a better monitoring and setting of the partial oxygen pressure in the head space of the container and, further, prevents a displacement of the oxygen as well as an introduction of the CO2 gas into the product located in the container as well as contact therewith. Due to the cyclone effect, moreover, the inventive apparatus exhibits an extremely high CO2 snow generating efficiency that nearly corresponds to the theoretical efficiency of 60%. The CO2 gas extraction means, in combination with the outer tube, can also be employed after the CO2 snow injection phase to extract the CO2 gas subsequently formed with the CO2 snow. The inventive apparatus thus enables an especially good cooling of the reaction processes with the cold content of the CO2 snow without the product to be cooled coming into contact with the CO2 gas to any noteworthy extent and being thus damages.
Examples of reaction processes in food stuff manufacture wherein the inventive apparatus can be utilized are:
1. Kneading wheat products: a process that must be essentially aerobic and oxidative and whereat additional frictional heat must be eliminated (reaching a specific dough temperature, for example 24.0xc2x0 C.). If the CO2 gas were to proceed into the dough, the necessary oxidation of the gluten proteins (the thiol groups in the proteins remain in the reduced condition) could, among other things, not occur and the desired dough development would be greatly reduced. A corresponding dough would not be elastic, would be discolored gray and the quality of the baked product would be extremely deteriorated.
2. Fermentation liquors: aerobic fermentations (for example, yeast production) require oxygen. At the same time, heat must be eliminated as a consequence of the metabolic action. When the CO2 gas in increased concentrations proceeds into the medium, the cell changes to an anaerobic metabolism, with the result that its reproduction is retarded or suspended (Pasteur effect). The consequences may be dramatic yield losses in terms of biomass. In another instance, fermentation formulas must be rapidly cooled from the fermentation temperature to a storing temperature or processing temperature (sour dough). The introduction of excessive quantities of the CO2 gas in the sour dough (CO2 solubility rises dramatically with low temperature) deteriorates the sensory (stifling smell and taste), hygienic (risk of the growth of aneroid bacteria) and the Theological properties (increased flowing). In the case of wheat sour doughs, oxidation processes are additionally minimized, important pigments are not formed (carotenoids) or protein SH groups are impeded in terms of their oxidation.
3. Fruit and vegetable processing: peeled apples or peeled potatoes but also salads (iceberg salad, etc.) can be preserved by water emersion baths (low-pressure container) specifically saturated with the CO2 snow. As a result thereof, an employment of preservatives (sulfites, etc.) can be avoided. The objective is, on the one hand, to introduce xe2x89xa77.0 g CO2/kg water and, on the other hand, to exploit the cooling effect. The high CO2 concentration enables both anti-microbial effects (reduction in the number of germs) as well as the minimization of enzymatic processes (xe2x80x9cenzymatic browningxe2x80x9d due to phenoloxidases) due to O2 displacement, and the like. The necessary CO2 concentration given simultaneous cooling effect can be achieved by dry ice (CO2 snow). The extraction of the CO2 gas is therefore also required for this process.
4. Grain mashes: in a malt house, grain is caused to germinate in germination boxes or the like at high water contents and elevated temperature (approximately 5 through 7 days). Cooling these mashes down to further-processing or, respectively, storing temperature dare not change the water content of the mashes and should be as fast as possible (due to the microbial risks) but without any CO2 gas (in order to avoid anaerobic processes for avoiding disadvantageous solubilization or extraction processes as well that occur due to the CO2 gas in solution). In a similar application, what are referred to as xe2x80x9cbrew batchesxe2x80x9d (cooked grain) in a bakery can be very rapidly cooled to further-processing or, respectively, storing temperature without changing the dough yield (water content) and without introduction of the CO2 gas.
5. Emulsifiers: the production of emulsions (water in oil, oil in water, multi-phase emulsions) requires the introduction of mechanical energy to a high degree with the assistance of specific homogenizing apparatus. The elimination of the frictional heat, the emulsification at defined temperatures and aerobic conditions (for example, 15xc2x0 C.) are critical pre-requisites for the reaction management. A displacement of air oxygen during the reaction by the CO2 gas would modify the reactivities at the phase boundary surfaces and would jeopardize the emulsification goal.
6. Raw meat mass: the production of raw meat mass ensues in the cutting house. For this process, great quantities of frictional heat (comminution work) must be eliminated and, on the other hand, work must be carried out at low temperature (for example +4xc2x0 C.) for hygienic aspects and technological reasons. The introduction of CO2 gas, in contrast (CO2 solubility in water-containing and high-protein sausage mass) is undesirable and leaves to hygienic, technological (consistency, etc.) and sensory disadvantages.
The inventive apparatus can also be of great assistance in maintaining the cooling chain when transporting food stuffs and other sensitive materials. With the assistance of non-stationary apparatus, for example, a suitable insulating container can be very easily xe2x80x9csnowedxe2x80x9d with the CO2 snow. When this is carried out at the upper part of the container, a uniform distribution of the snow from top to bottom occurs, and this causes a very uniform distribution on the repackaged food stuffs (cartons, etc.). As a result thereof, the desired transport or intermediate storing temperature of, for example, 18xc2x0 C. can be maintained over a long time (for example eight hours). Here, too, the active removal of the CO2 gas arising xe2x80x9cin statu nascenixe2x80x9d is necessary in order to assure adequate worker protection and working security (the enrichment of CO2 gas in the environment is intolerable for reasons of worker safety). When unpackaged food stuffs are to be cooled and transported in the insulated container (for example, open cream products, bakery products with unbaked filling, baked goods, sausages, etc.), then snowing with dry ice can ensue. CO2 gas (water as well) is to be avoided here, first in order to prevent a quality change of the product (taste, color etc.) and, on the other hand, in order to adhere to work protection and work safety.
Further features and advantages of the invention derive from the claims and the following description, wherein an exemplary embodiment is explained in